Solid fuel burning device



March 21, 1939. N. A. HALLSTRCM SOLID FUEL BURNING DEVICE Filed Oct. 28, 1957 2 Sheets-Sheet l BY WM ATTORNEY.

March 21, 1939. N. A. 1. HALLSTRCJM 2,150,970

SOLID FUEL BURNING DEVICE Filed Oct. 28, 1937 2 Sheets-Sheet 2 Patented Mar. 21, 1939 UNITED STATES PATENT OFFICE SOLID FUEL BURNING DEVICE Sweden Application October 28, 1937, Serial No. 171,441 In Sweden November 6, 1936 3 Claims.

My invention relates tosolid fuel burning devices, and particularly to devices of this type which are provided with a magazine for feeding fuel to the combustion chamber. Among the objects of my invention is to provide means for increasing the quantity of heat which may be transmitted from the burning fuel to the place of utilization of the heat and to limit the temperature of the burning fuel to such an extent as to prevent the formation of clinkers.

In any heating device, the quantity of heat which may be transmitted from the source of heat to the place of utilization depends upon the difference in temperature between the source and 15 the place of utilization, and the resistance to the flow of heat therebetween. In devices known to the prior art, the temperature of the place of utilization as well as the resistance to heat flow is substantially constant and hence it has been necessary to increase the temperature of the source in order to increase the quantity of heat. However, with coal burning devices, the upper temperature of the burning fuel is limited by the fact that high temperatures cause fusing of the ash, thereby producing clinkers which clog the grate.

In accordance with my invention, means are provided for decreasing the resistance to heat fiow, while at the same time limiting the temperature of the burning fuel to such an extent that the formation of clinkers is prevented.

Further objects and advantages of my invention will be apparent from the following description considered in connection with the accompanying drawings which form a part of this specification and of which:

Fig. l is a cross-sectional view of one embodiment of my invention;

Fig. 2 is a cross-sectional view taken on the line 22 of Fig. 1;

Fig. 3 is a cross-sectional view showing another embodiment of my invention; and

Fig. 4 is a cross-sectional view taken on the line 44 of Fig. 3.

45 Referring more particularly to Fig. 1, reference character l designates a casing for a stove or the like. Disposed within casing I0 is a metallic member II, the lower part 12 of which forms an ash pit while the upper part l3 defines a com- 0 bustion chamber. Insulating material I4 is preferably placed around member II within casing iii. A grate I5 is disposed within member H and separates the combustion chamber from the ash pit. A channel l6 connects the ash pit 55 with an ash pit door ll located at the exterior of casing [0. Door I1 is preferably provided with a thermostatically controlled damper for regulating the flow of air to the ash pit.

An annular member N3 of heat conducting material is located in heat transfer relation with the upper end of member H and serves to support a fuel magazine [9. The upper surface 20 of magazine I9 forms the place of utilization of heat, specifically the hot surface of the stove.

A lid 2| closes a central opening inthe upper 10 part of the magazine and may be removed for the purpose of filling the magazine with fuel. An insulating cover 22 is preferably provided for conserving heat when the stove is not in use. A flue 23 communicates with the interior of member l8 and leads to a chimney or the like.

Extending downwardly from magazine 19, and preferably cast integral with the magazine, are flat vane-like members 24 and 25. These mem bers terminate above the center of grate i5. The distance between the grate and the members 24 and 25 is such that, under normal operating conditions the upper surface of the burning fuel is some distance below these members while, during periods of abnormal combustion the lower ends of these members are disposed in the center of the burning fuel. These members are prefer ably fiat, as seen particularly in Fig. 2, in order that they will not interfere with the feeding of fuel from the magazine.

The above described device operates as follows:

Magazine I9 is substantially filled with solid fuel, which is supported by the grate l5 and confined by the sides of the combustion chamber I3. The fuel burns on grate I5, being supplied with air for supporting combustion through the damper in the ash pit door I1. The products of combustion pass upwardly through the annular space between the magazine IS on the one hand and the combustion chamber I3 and member l8 on the other hand, and finally pass through the flue 23 to the chimney.

Heat from the burning fuel is conducted through the walls of the combustion chamber 4 5 l3 and member [8 to the surface 20. These members, as well as the magazine l9, also absorb heat from the products of combustion as the latter pass to the fiue 23.

Under normal conditions the upper limit of the burning fuel is disposed below the lower ends of members 24 and 25. As the fuel is burned on the grate, the ash formed thereby passes through the grate and additional fuel is supplied by gravity from the interior of the magazine. Should it be desired to increase the rate at which heat is transmitted to the surface 20, this may be done by increasing the amount of air supplied through the channel IE to the burning fuel. This increases the rate of combustion and causes the fuel to burn up from the grate further, thus raising the upper level of the burning fuel. Ordinarily, this would increase the temperature to such an extent that the ash formed would be fused, thus forming clinkers. However, as soon as the upper level of the burning fuel reaches members 24 and 25, these members serve to conduct heat to the magazine and thence to the surface 20. Inasmuch as members 24 and 25 were previously substantially ineffective in conducting heat, the resistance to flow of heat to the surface 20 has now been reduced considerably. At the same time this rapid flow of heat from the center of the burning fuel serves to limit the temperature attained therein to such a value that the formation of clinkers is prevented.

The embodiment shown in Figs. 3 and 4 is similar in the principle of operation to that already described. The structural differences between the two devices reside in the fact that members 24 and 25, which are integral with the fuel magazine in Fig. 1, are replaced by flat members 26 and 21 which are integral with the walls of the combustion chamber l3. The lower edges of members 26 and 21 are disposed a distance above grate l5 such that the members are above the upper level of the burning fuel under normal conditions, but extend into the burning fuel under conditions of abnormal combustion. Members 26 and 21 serve to conduct heat under these conditions to the walls of the combustion chamber l3 from whence it flows to the surface 20.

While my invention has been described in connection with a device in which solid fuel is fed by gravity, it is to be understood that it is applicable as well to devices using stokers or the like in which fuel is fed mechanically. Moreover, in the embodiments illustrated, the heat conducting members 24 and 25 or 26 and 21 have been disposed vertically above the grate. This is because the products of combustion in these embodiments flow vertically upwardly from the grate. Should the arrangement be such that the products of combustion flow in some other direction, the heat conducting members shoud be disposed away from the grate in such direction. This is because the direction of flow of the products of combustion determines the direction in which the fuel will burn upon an increase in the rate of combustion.

The scope of my invention is not to be limited by the above described embodiments, which are merely illustrative of my invention, but is to be determined by the appended claims viewed in the light of the prior art.

What I claim is:

1. In a combustion device for burning solid fuel, a grate, a magazine for feeding fuel to said grate, means surrounding the burning fuel on said grate for conducting heat therefrom under all conditions of combustion, and means extending from said magazine to above the center of said grate for conducting heat from the center of the burning fuel under abnormal conditions of combustion.

2. In a combustion device for burning solid fuel, metallic walls forming a combustion chamber, a grate, means for feeding fuel to said grate, said metallic walls serving to conduct heat from the burning fuel under all conditions of combustion, and means extending from said walls to above the center of said grate for conducting heat from the burning fuel under abnormal conditions of combustion.

3. In a combustion device for burning solid fuel, a grate, a magazine for feeding fuel to said grate, means surrounding the burning fuel on said grate for conducting heat therefrom under all conditions of combustion, and a member disposed between said magazine and said grate and above the center of said grate for conducting heat from the burning fuel under abnormal conditions of combustion, one of the horizontal dimensions of said member being small whereby to permit the free feeding of fuel.

NILS AUGUST IVAN HALLsTRoM. 

